Author's Conclusions

The relative reduction is the same for all age groups, but the absolute benefit was greatest in younger women (10% at 40 yr, but only 3% in patients over 50)

The boost was associated with a higher incidence of severe fibrosis

Clinical/Scientific Implications

A tumor bed boost is effective in reducing local recurrence, but the price is a higher, but still infrequent incidence of fibrosis

Despite being powered to detect a 5% difference in survival in this very large trial, there was no difference in overall survival.

Like all adjuvant therapies, the decision to use adjuvant radiation with or without a boost should be individualized to the patient's risk of recurrence, expected survival, and tolerance of excess recurrences from "under treatment."